1、challenge

挑战;难题

I like a big challenge and they don't come much bigger than this.

我喜欢大的挑战，而所有挑战中再没有比这更大的了。

The new government's first challenge is the economy.

新政府面临的第一个难题是经济问题。

(成功地)应对挑战，迎接挑战

The new Germany must rise to the challenge of its enhanced responsibilities.

一个崭新的德国必须迎接挑战，承担更多的责任。

They rose to the challenge of entertaining 80 schoolchildren for an afternoon.

他们一个下午成功接待了80名学童。

怀疑，质疑(真实性、价值、权威等)

Democratic leaders have challenged the president to sign the bill.

民主党领袖对总统签署这项法案提出了质疑。

The move was immediately challenged by two of the republics.

此项动议立即遭到其中两个共和国的反对。

2、reaction

反应；回应；反响

Reaction to the visit is mixed.

对这次访问的反应不一。

The initial reaction of most participants is fear.

多数参与者的最初反应是恐惧。

反对;反抗;抵制

All new fashion starts out as a reaction against existing convention.

所有新时尚都是从打破现有常规开始的。

Her three years of freedom seemed like a reaction against that childhood.

她那3年的自由仿佛是对孩童时代的反叛。

抵制；抵触

Premature moves in this respect might well provoke a reaction against the reform..

在这方面不成熟的举动很可能引发对改革的抵触情绪。

The government response seems to be the result of strong public reaction against the police apathy.

政府的回应似乎是公众强烈抵制警察冷漠执法的结果。